Olefin/maleic anhydride copolymers of low molecular weight



I known for many years.

1 a 2,938,016; OLEFlN/MALEIC'iANHYDRIDE? COPOLYMERS or Low MOLECULAR-WEIGHT ilohnfl. .Iohnson, Daytoml Ohio, assignor' to Monsanto Chemical'Company, St; Louis, Mo., a corporation of Delaware 7 l No Drawing. Filed Aug.-10,1956, Ser. No. 603,211

' 17 Claims. or. 260-785 v This invention relates tothe production of low molecular weight olefin/maleic anhydride copolymers. In some v proportions of maleic anhydride and the olefin combined therein. The copolymerization is advantageously'efiected by'subjecting a. solution of maleic anhydride in an organic diluent, e.g., benzene,'to a superatmospheric olefin pressure, employing a peroxide catalyst and elevated temperatures. .In many. instances where a comparatively high molecular weight copolymer is desired, this procedure is adequate. However, it has been found difiicult to produce low molecular weight olefin/maleic anhydride copolymers, whichfind various uses such as deflocculants and thinners for drilling muds and dispersants for pigments. While especially elevated temperatures, e.g., those above 100 C., tend to result in a product of lowered molecular weight, the physical form is not desirable; it

I appears that the high temperatures cause a softening of the copolymer product which-forms as a'more or less in.-

: soluble solid in suspension in the diluent. or solvent used, and the softened particles of polymer tend to agglomerate,

as well as accumulate on-the walls of the reaction vessel and stirrer, if any isrused. While for many polymerizations an incre'asein the amount of catalyst causes a-decrease in molecular weight of the polymer, this particular system is not very sensitive to catalyst concentration at least insofar as reflected in a change in molecular weight.

In accordance with the present invention in preferred aspects, the copolymerization of maleic anhydride with a C to C olefin is effected in the presence of an aldehyde having the formula wherein R is selected from the group consisting of hydrogen, hydrocarbon radicals, and aldehyde-substituted hydrocarbon radicals. Those'having at least one hydrogen atom on the a-carbon atom, i.e;, on the carbon atom attached to the ---CH group, are preferred; such com= Un cd Stews P tc t 0 pounds wherein R is alkyl are often most conveniently used, and can be termed alkanals having at least one hydrogen atom on the oz-carbon atom. Other preferred aldehydes are those in which the a-carbon atom, has one or two hydrogen atoms and also is substituted byan'aryl radical through aromatic carbon. The materials employed in the inventioncan be generally described aldehydes free from non-hydrocarbonsubstituents'i While aldehydes having more than one aldehyde group in th'e molecule, e.g., dialdehydes', trialdehydes, etc. ,-ca'1i beused, such polyaldehydes are often diflicult to* manufacture and/ or store; hence the monoaldehydes are'almost always preferred.

The aldehydes employed in the present invention permit the production of ethylene/maleicanhydride copolymers, propylene/maleic anhydride copolymers, andbutene/mal'eic anhydride copolymers, having low molecular weights desired for certain purposes, and have marked advantages over certain other types of compounds which also result in the production of low molecular weight copolymers in that the yield is only moderately reduced at a, given concentration of catalyst, usually a peroxide, and essentially theoretical yields are readily obtained by only modest increases in the concentration of the catalyst,

By way of example, but not limitation, of suitable aldehydes that can be employed in practicing the present invention, there are mentioned: formaldehyde, -acetaldehyde; ropion'aldehyde', n-butyraldehyde, isobutyraldehyde, trimethylacetaldehyde, iso-valeric aldehyde, stear'aldehyde, phenylacetaldehyde, diphenylacetaldehyde,cycle hexylformaldehyde, A -cyclohexenylformaldehyde,A pen ten-l-al, glyoxal, benzaldehyde, u-naphthaldehyde-"fi? naphthylacetaldehyde, m-phthaldehyde, 1 p-phenyle'ne-bis- (acetaldehyde), OX0 aldehydes, i.e., aldehydes derived by reaction of olefin hydrocarbons with CO and H 'by'the 0x0 process, and especially when the olefin is a polymer or mixed polymers of propylene and/ or isob-utylene, e.g., such polymers containing from 8 to 16 carbon atoms; There is usually no advantage in the aldehydes having more than 25 carbon atoms per molecule; and those having from 2 to'15 carbon atoms per molecule'arepreferred. i

The quantity of the particular aldehyde employed' will fall within a rather wide range. A preferred" range is from 0.5 to 20 mole percent of the aldehyde, based on the reacting monomers (assuming conversion) i.e., from 0.5 to 20 moles of the aldehydeper 50 moles maleic anhydride charged (50" moles maleic anhydride will theoretically react with 50 moles of tlie ol efin,thus'"ma'king 100 moles of reacting monomers). The same basis is meant herein when mole percent catalyst ismenti'on'ed'. For most purposes I prefer to use from 3 to l0 mole percent of the aldehyde. At otherwise fixed reaction conditions, the higher the percentage of a givenaldehyde the lower the molecular weight of the resulting copoly mer. The amount of aldehyde used is one of several inter dependent reaction variables which affect the molecular weight of the product. The more important ofthe other such variables are the reaction temperature and the re action pressure (upon which the hydrocarbonmonomer concentration depends). temperature, the lower the molecular weight, and the higher the pressure, the higher the molecular weight. However, the temperature should not be increased too much for the reasons discussed hereinabove. Also, the pressure should not be lowered too much orthe yield of copolymer tends to decrease to an undue'extent.- Lower Patented May 24,j 19.6 0

In general, the higher the" pressures are more suitable in the cases of propylene and isobutylene copolymers where the vapor pressures of the olefin at a given temperature are lower than in the case of ethylene. I prefer to employ a reaction temperature within the range of 40 to 80 C., and 60 to 80 C. is especially advantageous. At such temperatures, the reaction rate is good and the physical form of the copolymer product is good. The reaction pressure can be atmospheric or below, but is preferably super-atmospheric. It is preferred that the reaction be carried out in a closed vessel such as a stirred autoclave, rocking bomb, tubular reactor through which reaction mixture flows, or the like, at a pressure above atmospheric pressure. The pressure is preferably above 100 pounds per square inch gauge for the preparation of ethylene/maleic anhydride copolymers, and pressures of 150 to 400 pounds per square inch gauge are especially preferred. However, even higher pressures, say up to 1000 pounds per square inch gauge and above, are permissible. As pointed out hereinafter, in general, the higher the pressure the higher the mo lecular weight and hence the greater the quantity of alde. hyde required.

The olefin reactant can be a single olefin or a mixture of any two or more of the olefins ethylene, propylene, isobutylene, butene-l, butene-Z-cis, and butene-2-trans. Preferred olefins are ethylene, propylene and isobutylene. While the maleic anhydridecopolymers of these olefins have many attributes in common, there are also important differences among the products as well as among the optimum ranges of reaction conditions to be employed in making them. Thus reaction pressures can be significantly lower when higher boiling olefin monomers are used. For example, adequate olefin monomer concentration can be obtained at pressures ranging from 50-200 p.s.i. when propylene is involved; with isobutylene, essentially atmospheric pressures are suflicient, but higher pressures can be used. The properties of the copolymers differ markedly with the olefin monomer with particular reference to acid strength of the copolymers which have been hydrolyzed to the free acid form and chemical reactivity of both the anhydride and the acids. In general, the greater the degree of substitution on the ethylene group, the lesser are both acid strengths and chemical reactivity (i.e., ease of esterification, etc.). The invention will be discussed in more detail referring to ethylene/maleic anhydride copolymers by way of example, and application of same to the other olefins will be apparent, bearing in mind the foregoing comments.

The copolymer product contains essentially one mole of total olefin per one mole of maleic anhydride combined therein, irrespective of the relative proportions of ethylene or other olefin or mixture of olefins on the one hand, and maleic anhydride on the other hand, introduced to the reaction system. The ratio of free olefin, e.g., ethylene, available for reaction, to free maleic anhydride available for reaction, at any given time depends upon a variety of factors, including particularly the quantity of free maleic anhydride dissolved in the solvent and the quantity of ethylene dissolved in the solvent. The latter value in turn depends upon the solubility of ethylene in the reaction mixture, which is a function of the particular solvent, the temperature, the pressure, and the concentration of maleic anhydride in the solvent. It is much preferred that by the time the reaction has been completed, an excess of ethylene over that required to react with the entire quantity of maleic anhydride shall have been furnished to the reaction mixture, so as to give maximum utilization of the maleic anhydride. (This is less necessary with propylene and isobutylene, and with these olefins, especially the latter, an efiective manner of operating is to charge initially all the maleic anhydride and less than the stoichiometric amount of olefin and intermittently or continuously add olefin until the total charged is just equal to or slightly more than the stoichiometric quantity.) Any unreacted ethylene is readily recoveredand recycled to the reaction. The ethylene, maleic anhydride, solvent or diluent, and aldehyde can be brought together in various ways, but in any event thorough intermixture of same should be provided. Thus, the reaction can be conducted in a batch, into which ethylene is continuously or intermittently added to maintain pressure until all the maleic anhydride is used up by copolymerization. A similar operation can be conducted wherein maleic anhydride is added continuously or intermittently. The components of the reaction mixture can be continuously fed into a stirred autoclave withcontinuous overflow of total reaction mixture out of the autoclave either to recovery steps or through a series of autoclaves. A total reaction mixture can be passed through an elongated reaction tube, with ethylene and/or maleic anhydride and/or catalyst and/or aldehyde being added at one or more points along the length of the tube if desired.

It is most convenient to carry out the reaction in the presence of an organic solvent for the maleic anhydride. Such solvent is preferably also a non-solvent for the copolymer product. Such materials which can be termed solvents or diluents are advantageously aliphatic or aromatic hydrocarbons or chlorinated hydrocarbons, for example, benzene, toluene, xylene, n-hexane, mixed hexanes, octane, ethylene dichloride, propylene dichloride, chlorobenzene, the dichlorobenzenes, and the like. Since the solvent preferably has a high capacity for dissolving maleic anhydride, it is desirable when apoor solvent for maleic anhydride, such as hexane, is employed to have mixed therewith a good solvent for maleic anhydride, such as ethylene dichloride or benzene. While the proportion of the total solvent to the other components of the reaction mixture can be varied over a wide range, it is preferred to employ an amount such that the final reaction mixture will have a solids content (calculated on the assumption that all maleic anhydride has copolymerized) within the range of 5 to 30 weight percent.

The copolymerization is effected in the presence of a catalyst of free-radical promoting type, principal among which are peroxide-type polymerization catalysts and amtype polymerization catalysts. Those skilled in the art are now fully familiar with a large number of peroxidetype polymerization catalysts and a suitable one can readily be chosen by simple trial. Such catalysts can be inorganic or organic, the latter having the general formula: R'OOR", wherein R is an organic radical and R is an organic radical or hydrogen. These compounds are broadly termed peroxides, and in a more specific sense are hydroperoxides when R" is hydrogen. R and R" can be hydrocarbon radicals or organic radicals substituted with a great variety of substituents. By way of example, suitable peroxide-type catalysts include: benzoyl peroxide, lauroyl peroxide, tertiary butyl peroxide, 2,4-dichlorobenzoyl peroxide, tertiary butyl hydroperoxide, diacetyl peroxide, diethylperoxycarbonate, dimethylphenylhydroperoxyinethane (also known as cumene hydroperoxide), among the organic peroxides; hydrogen peroxide, potassium persulfate, perborates and other per compounds among the inorganic peroxides. The azo-type polymerization catalysts are also well known to those skilled in the art. These are characterized by the presence in the molecule of the group -N=N- wherein the indicated valences can be attached to a wide variety of organic radicals, at least one, however, preferably being attached to a tertiary carbon atom. By way of example of suitable azo-type catalysts can be mentioned a,a'-azodiisobutyronitrile, p-bromobenzenediazonium fluoborate, N-nitroso- Why: the; solvent.

' action mixture is preferred.

.soluble in the reaction mixture.

gcopolymer product. .any conventional drying procedure to remove any residu'al solvent. As an alternate procedure for isolation, the

p-bromoacetanilide, azomethane, phenyldiazonium halides, diazoaminobenzene, p-bromobenzenediazonium hydroxide, p-tolyl diazoaminobenzene. The peroxy-type or azo-type or other free radical promoting type of polymerization catalyst is used in small but catalytic amounts, which generally are not in excess of- 1 to 2 mole percent,

based on the reacting monomers as above defined.--A. suitable quantity is often in the-range-of 0:1- to- 1.0-molepercent.

It is an important advantage of the present invention that the aldehydes, while quite active in reducing the molecular weight of the copolymer product, do not seem to stop the chain transfer reaction to a severe extent and hence even with comparatively large amounts of the added aldehyde, it is necessary to increase the catalyst concentration only a very moderate amount. Furtherinformation is supplied in the examples given hereinafter. The quantity of the aldehyde employed will be chosen which, in combination with the other reaction variables, will result in the production of an ethylene/maleic anhydride copolymer having a specific viscosity less than that obtained if the said aldehyde is not used. In general, the specific viscosity should be not in excess of about 0.3, as determined on a one weight percent solution of the copolymer product in dimethylformamide, the viscosity measurement being made at 25 C. The preferred range of specific viscosities for ethylene/maleic anhydride copolymers is from 0.05 to 0.2, and a value of less than 0.15 is preferred for most uses to which the copolymer may be put. Since there are certain inherent viscosity differences depending upon the olefin employed, the preferred range of specific viscosities for the aldehyde regulatedcopolymers will vary. This is due to the effects of olefin substitution upon the degree of coiling for the polymer chain which results in varying solution viscosities. for different polymers of equivalent molecular weights. Thus, the preferred specific viscosity range for propylene/maleic anhydride copolymer is from 0.10 to 0.40 and for isobutylene/maleic anhydride copolymer from 0.20 to 1.0. To obtain polymers having these specific. viscosities, the amount of aldehyde employed will in most cases be within the range of 1 to 20 mole percent based on reacting monomers as hereinabove defined. Any unreacted aldehyde remaining present inthe final'reaction mixture can be recovered and returned to V the process forfurther use. A preferred embodiment of myinvention involves separatingthe copolymer product by'siinple filtration, centrifuging, or the like from the total liquid (which includes solvent, aldehyde, and any unreacted maleic anhydride dissolved therein) and recycling the total liquid for further use in the polymeriza- .po surerto moisture has occurred and the maleic anhydride' .is contaminated with maleic acid, it is preferred to .dissolve the material in the solvent to be used in the reaction; and separate by filtration. or centrifuging or .otherwise any-maleic acid present, which is not dissolved I In other words a maleic acid-free re- As pointed out before, the .copolymer' product generally separates as a solid in- It can be separated therefrom-by centrifuging or filtration as desired,'and

vthen is preferably washed with a hot organic solvent for maleic anhydride, such as benzene at 100 F., sufiicient- 1y to remove any unreacted maleic anhydride from the The copolymer is then subjected to in dimethylformamide, and the specific viscosity deter- V polymer slurry can be direct dried in a vacuum-pan drier.

The low molecular weight olefin/maleic anhydride copolymers produced by the practice of the present invert-1 tion find particular use as dispersauts. in numerous industrial fields. They have been found to be outstanding 7 ments, for clay slips used in the ceramics industry, for

clay coatings for paper, and the like. The copolymer can be employed as such, i.e., in the anhydrideform; and hydrolysis to the free acid or salt, if salt-forminglmaterials are present, occurs in the. aqueous mediumin which the polymer is being used. Alternatively, the copolymer before use can first be converted to the f'r'ee acid form by hydrolysis, or to the-form of its alkali metal or other metal salts, ammonium salts, amine salts, partial or complete ester or amide, and the like, as may be desired for any particular purpose.

The following examples are provided to give ,anindication of suitable reactants, solvents, catalysts, and'aldehydes, and proportions of same, as well as suitabletemperature and pressure conditions for the copolymeri zation. However, it will be understood that variations from these specific examples can be made without departing from the invention.

EXAMPLES 1-18 flushing procedure the reaction mixture was'freed'of'any' dissolved air. The bomb was then charged with "sufficient ethylene to give an estimated 200 p.s.i.g. (100 p.s.i.g. in Examples 13 and 14) pressure on heating to the chosen reaction temperature of 70 C. or C.

Rocking of the bomb was started, and the contents brought up to reaction temperature by means of an electrically heated jacket. Additional ethylene was charged into the bomb from time to time to maintain the chosen pressure of 200 p.s.i.g. p.s.i.g. in Examples 13 and 14). In most of the examples the run continued overnight so the total time was 16 to 24 hours; however, the copolymerization reaction was completed. in from 10 to 20 hours, varying from example to example.

Unreacted ethylene was vented, the total reaction mixture was filtered, the separated ethylene/maleic anhydride copolymer was washed several times with benzene or ethylene dichloride while filtering, and. the polymer I was then dried at 100 C. for 24 hours under the full vacuum of a water aspirator. Yield was calculated as percent of theory, based on 100% of maleic anhydride being copolymerized with ethylene in lzl'moleratio.

The specific viscosity of the polymer product was determined by modification of ASTM Method D-445-46T, Method B, using an Ostwald type viscosimeter. The polymer was dissolved in 1 weight percent concentration mined at 25 C.

Table I.

' Table l PRODUCTION 08' LOW MOLECULAR WEIGHT EIHYLENE/MALEIO ANHYDRIDE COPOLYMER WITH THE AID F BUTYRALDEHYDES Benzoyl EMA Copolymer Aldehyde. Malelc Solvent, Peroxide, Temp, Example Wt. Anhydrlde, ml. mole 0. Comments Percent 1 grams Percent Yield, Sp.

Percent Vise.

Benzene 0 200 1, 600 0. 70 99. 8 0. 36 Control. 0 267 2, 089 0. 5 80 96. 8 0. 23 D0. 1. 25 200 1, 600 0. 5 70 98. 5 0. 31 1. 40 200 1, 600 O. 5 70 97. 3 0. 25 2. 50 200 l, 600 0. 5 70 98. 6 0. 24 5. 00 200 1, 600 0. 5 70 98. l 0. 18 5. 00 200 1, 600 0. 5 80 98. 1 0. 14 7. 00 200 1, 600 0. 5 80 97. 4 0. 12

8. 0 364 2, 089 0. 5 80 83.8 0. Solids. 9.0 267 2, 089 0. 5 80 94. 6 0. ll 10. 9 267 2, 089 0. 75 80 93. 0 0. 09

1. 4 200 l, 600 0. 5 70 96. 2 0. 26 Isobutyraldehyde.

Ethylene Dichlorlde 0 267 2, 089 0. 5 80 97. 2 0. 16 Control. 9. 0 267 2,089 0. 5 80 78. 2 0. 11 9. 0 267 2, 089 0 75 80 98. 5 0. 10 9. 0 267 2, 089 0. 75 80 79. 6 0. 08 100 p.s.l.g. 9. 0 267 2, 089 1. 5 80 95. 9 0. 07 Do. 10. 0 364 2, 089 1.0 90 98. 3 0. 10 20% Solids. 10. 9 267 2, 089 0. 75 80 96. 9 0. 10 18. 0 267 2, 089 0. 75 80 98. 1 0. 09 10. 9 267 2, 089 0. 75 80 92. 4 0.09 lstlalbultyralde- I Wt. Percent=g. aldehyde per 100 g. reacting monomers; multiply by 0.875 to give mole percent aldehyde.

Examples 1 to 9 when compared with each other and with the controls show the lowering of molecular weight of the ethylene/maleic anhydride copolymer obtained by the use of n-butyraldehyde. As shown in Example 1, even 1.25 weight percent gives a definite lowering of viscosity as compared with the control wherein no aldehyde was employed. Increasing the amount up to 5% causes a continued and marked decrease in specific viscosity of the product. Comparison of Example 5 with Example 4 reveals that an increase of 10 C. in the reaction temperature causes a definite decrease in the molecular weight of the product. Proceeding to Example 6, increasing the percentage n-butyraldehyde from 5 to 7 percent causes a still further decrease in molecular weight of the product as shown by lowered specific viscosity. Example 7 reveals that an increase in the amount of maleic anhydride charged without otherwise markedly changing the reaction variables, resulting in a 20 weight percent solids slurry as final product if all the maleic anhydride is converted to the copolymer, did not significantly change the properties of the product. The lowered yield is believed due to possibly poor agitation caused by the increased solids content. This was not present in a similar run wherein the solids content was 20 percent but the solvent was ethylene dichloride, as shown by Example 15. Examples 8 and 9 show that continued increase in the per centage aldehyde caused continued decrease in the specific viscosity of the polymer product, although the rate of decrease in specific viscosity of the product in going from 5 to 7 to 9 to 11 percent aldehyde in Examples 5, 6, 8 and 9 is not nearly so marked as the rate of decrease which occurred with incremental changes at the lower percentages of aldehyde.

Example 10, which can be compared with Example 2, shows that substitution of isobutyraldehyde for n-butyraldehyde does not significantly change the results obtained. Comparison of Example 18 with Example 16 shows the same to be true when ethylene dichloride is the solvent.

The ethylene dichloride control shows, on comparison with the benzene 80 C. control, that ethylene dichloride alone effects some lowering of molecular weight. Examples 11 to 18 show that when ethylene dichloride is employed as solvent the molecular weight of the product is about the same as that obtained with benzene as solvent, when the aldehyde is employed in similar concentration. Ethylene dichloride does appear to require somewhat more catalyst to obtain high yields. An important difference, not shown in the table, is that the product obtained when ethylene dichloride rather than benzene is used as solvent, has a much higher bulk density and does not have nearly as great a tendency towards dusting. These improved properties are believed to be the result of the greater non-solvent character of the ethylene dichloride for the polymer (i.e., the polymer is less swollen in the solvent than in benzene).

Example 11, on comparison with Example 8, shows that the product specific viscosity is not changed by the change in solvent although the yield is somewhat lowered. Example 12, by increasing the catalyst quantity one-half, namely from 0.5 to 0.75 mole percent benzoyl peroxide, resulted again in a high yield of product.

Examples 13 and 14 were run at p.s.i.g., rather than the 200 p.s.i.g. used in all the other examples. Example 13 shows that the lowered pressure markedly dropped the yield, while Example 14 shows that this effect can be overcome and the yield brought back to nearquantitative by doubling the amount of catalyst. Examples 13 and 14 also show that the lower pressure permits the production of polymer product of still lower molecular weight, as shown by the specific viscosity.

Example 15 shows that an increase in the solids content of the reaction mixture to 20 percent, this being the theoretical solids content based on complete conversion maleic anhydride charged to ethylene/maleic anhydride copolymer, does not result in any significant change in the polymer molecular weight. It will also be noted that the yield was not decreased as was noted in Example 7, presumably because of the more readily stirrable form of the polymer when using ethylene dichloride as solvent.

Examples 16 and 17 demonstrate that aldehyde concentrations in the neighborhood of 10 weight percent give about the maximum regulating action in the preparation of ethylene/maleic anhydride copolymer, since the specific viscosities of the product obtained with 10.9 percent aldespasms EXAMPLES 19 TO 27 In the same apparatus and bythe same-procedure .employed for Examples-1 to-18 two series of runs-weremade to eyaluate. the possibility of recycling unused nfbuty raldehydmand. solvent. 'I heresults of the two seriespflrunsare given in Table II. The n-butyraldeydei wasz dded on y' o-t r rst r fme ie T polymerization was carried out as described above,,the polymer product was recovered by filtration; and the next subsequent trun of the series was. made using. the filtrate from the preceding run with sufiicient ethylene dichloride solvent added to makeup to volume. The power of this system-to maintain the production of low molecular weight ethylene/maleic anhydride copolymer remained virtually constant through about, foursuccessive runs and then appeared to diminish at a slow rate. Reaction times were not adversely affected by this procedure. Also, if the polymer yield was low in one run the. .yield was correspondingly high in the next. since unreacted rnaleicanhydridewas also being recycled.

T6 EXAMPLES 28-31 In the same apparatus and by thesame general procedure employed for the earlier examples, propylene was copolymerized with maleic anhydride. Data are given in Table III.

Comparison of Examples 28 and 2;9 with the control 1 reveals the much lower molecular weight (as indicated by specific viscosity) obtainable in the propylene /rjnaleic anhydride copolymer through use of n-butyraldehyde. Examples 28 and 29 also show the effect ofltempe'ratiire on molecular weight. Examples 31 and-29-taken-to; gether show that substitution of benzenefor' ethylene dichloride does not greatly affect the results (the total' weight of propylene fed in ,these twoi' examples was about the same, and the pressure inExample 29 startedahove and ended below the pressure maintained iii Example 31). The small amount of propylene used in Example 30 (with the correspondingly lowpressui'e'o'f50'to 20 p.s.i.g.) resulted in a yield of only 52%, but the. molecular weight was the lowest amongst the propylene/maleic anhydride examples.

muds; such as those obtained by suspension of .bentonitein water, with or without weighting --materialsfsuch'.as:

barytes; the copolymers should be used in. quantities o'ff from 1 to 4 pounds per barrel of drilling n'rudI Table III PRODUCTION- OF 'LOW MOLECULAR WEIGHT PROPYLENE/MALEIC ANHYDRIDE OOPOLYMER WITH THE AID OF n-BUTYRALDEHYDE At'otherwise the same conditions; 1 increased propylene, and perhaps the inci'easedcatalyst;

n-Butyral- Propylene Benzoyl PMA Co 01 men dehyde, Malerq An- Propylene/ Solvent, Peroxide, Temp, p y Example Mole hydride, MA, mole ml. mole C.

. Percent grams ratio grams p.s.i.g. Percent Yield, Sp; Percentv Visc;

Ethylene dichloride Benzene 1 In the Control and Examples 28, 29v and 30, the stated weight oi propylene was charged initially and no other propylene was later added. In Example 31, propylene (amounting to a total of 177 g.) was charged periodically to maintain the stated pressure.

Table II PRODUCTION OF LOW MOLECULAR WEIGHT E'IHYLENE/ MALEIC ANHYDRIDE COPOLYMER, WITH RECYCLE OF n-BUTYRALDEHYDE 6 EMA Oopolymer' n-Butyraldehyde',Wt. Percent Example Yield;

Sp. Vise; Percent 9.0 99. 6 residue from Ex.-

, residue 'froni Ex.

residue from Ex. 24 residue from Ex. 25 residueirom Ex.

ltialeic 200 g. chargedeach example; ethylene 200 p.s.i.g.; ethylene-dichloride2089 ml. .(filtrate plus make-up ethylene dichloride); reaction temperature stlisq; henzoylperox de 0.75 mole percent charged each example.

EXAMPLES 32-35 Propyleneand maleic anhydride were copolymerized 9 as in Examples 28-31 in a series of tests showing theeffect of varying the propylene/maleic anhydride ratio.

Table IV EFFECT OF REDUCING PROPYLENE/MALEIO ANHYDRIDE RATIO n But al I Propylene Benzo 1 PMA Copolymer dehyYI e, Maleic An- Ethylene Pcroxiii e, Temp., Example mole hydride, Initial Initial Pressure Dichlomole C.

Percent grams Charge, P/MA, Mainride, ml. Percent Yield, Sp.

g. mole tained, Percent Vise.

ratio p.s.i.g.

9. 75 147 12a 2: 1 120 1, 200 0. 75 so 100 0. 30 as as 2: as s 1 23:; 2a a a; s a 91 75 19s 42 b. s51 40 11 600 oI 75 so 971 6 01 16 EXAMPLES 36-40 While the invention has been described with particular reference to preferred embodiments thereof it will In the same apparatus and by the same general procedure employed for the earlier examples, isobutylene gf ggg i s gz z g gil i ffi gg g igggg ig fiz was copolymenzed w1th malelc anhydride in the presence b 2 t a cts P g of n-butyraldehyde. Data are presented in Table V. gi

In each instance, the stated weight of isobutylene was 20 m further was res lessness:eibezzazsz ar srs urm e run.

It interesting to note that in Examples 37 and 38, of a.free'radl?al pmmotmg catilyst to form olefin, in which neither reactant was present in excess, theoretii afinhyqnde P i the.1m1?rvement which cal yields were nevertheless readily obtained. The data ecgmg i gggf zgg g a z fii gf g also show that the catalyst requirement for isobutylene/ i d f ul p maleic anhydride copolymerization in the presence of a e y e a mg e mm a n-butyraldehyde is quite low. Increasing the isobutylene (Example 36) to give an isobutylene:ma1eic anhydride 1 c= 1.6 h 3235 3; i g g gj gfg g g gfigr gg fi i wherein R is selected from the group conslstmgof hydrogen, hydrocarbon radicals, and aldehyde-substituted hylb tdthtthl dhildSl desa Z {fi b a e X g drocarbon radicals, said aldehyde being present 1n an a e so-ven an enzene m ma ng ene amount within the range of 0.5 to 20 mole percent based anhydride copolymer because the polymer 1s obtained m on the reacting monomers itfi fiiiiniiiii ini 335,153? 8% ili vfhiifi i ofiiii i the coplymaizafion of maleic anhydride with in :1 better inore dense phy sica l fc n m when ethyle e ethylene with the aid a free'raqical Promoting catalyst to form ethylene/maleic anhydride copolymer, the 1michloride 1s the solvent. Example 39 shows that lowerovement which com rises effectin said co o1 meriza in th mount of isobut lene lowersth molecular we ht g P y g ea y e t t t m :11 40: 80C d of the product The increased amount of n-butyraldenon a a empera ure W1 e ranfgeo o an 40 in the presence of an aldehyde having the formula hyde in Example 40 resulted in the lowest molecular weight product, despite the fact that isobutylene was present in excess.

Table V PRODUCTION OF LOW MOLECULAR WEIGHT ISOBUTYLENE/MALEIO ANHYDRIDE COPOLYMER WITH THE AID OF n-BUTYRALDEHYDE n-But'yr- Maleic Isobutyl- Benzoyl IBMA Copolymer aldehyde, Anhy- Isobuene/Malelc Solvent, Peroxide, Temp, Example mole dride, tylene, Anhydride, m1. mole 0.

percent grams grams mole ratio percent Yield, Sp.

percent Vlsc.

Ethylene dichloride Benzene 1 In Example 39, tyleld is based on isobutylene, since the malelc anhydride was present in excess of the stolchiometrlc amoun The isobutylene/maleic anhydride copolymer products of Examples 36-40 are all useful as sizes for textiles, especially rayon cloth. In this use the low molecular drogen, hydrocarbon radicals, and aldehyde-substituted.

hydrocarbon radicals, said aldehyde being present in an weights are advantageous in providing aqueous sizing 70 amount within the range of 0.5 to '20 mole percent based solutions of sufiiciently low viscosity to permit easy handling and a more uniform sizing than obtainable with isobutylene/maleic anhydride copolymers made under the same conditions but in the absence of the n-butyraldehyde.

on the reacting monomers.

3. In the copolymerization of maleic anhydride with propylene with the aid of a free-radical promoting catalyst to form propylene/maleic anhydride copolymer, the

76 improvement which comprises effecting said copolymerization at a temperaturemithiii.themangeof 40 to 80 C.

was the. grasses; aelstehx s. arins he wmm isobutylene. with the aid of a free-radical promoting catalyst to form isobutylene/maleic anhydride copolymer, the improvement which comprises effecting said copolymerization at a temperature within the range of 40 to 80 C. and in the presence of an aldehyde having the formula H Ill-(i= wherein R is selected from the group consisting of hydrogen, hydrocarbon radicals, and aldehyde-substituted hydrocarbon radicals, said aldehyde being present in an amount within the range of 0.5 to 20 mole percent based on the reacting monomers.

5. In the copolymerization of ethylene with maleic anhydride with the aid of a free-radical promoting catalyst to form an ethylene/maleic anhydride copolymer, the improvement which comprises effecting said copolymerization at a temperature within the range of 40 to 80 C.

, within the range of 0.5 to 20 mole percent based on the reacting monomers.

7. In the copolymerization of ethylene with maleic anhydride with the aid of a free-radical promoting catalyst to form an ethylene/maleic anhydride copolymer, the improvement which comprises eifecting said copolymerization at a temperature within the range of 40 to 80 C. and in the presence of isobutyraldehyde in an amount within the range of 0.5 to 20 mole percent based on the reacting monomers.

8. A process which comprises subjecting maleic anhydride maintained under an ethylene pressure of at least about 150 pounds per square inch and at a temperature within the range of 60 to 80 C. to polymerization with the aid of a peroxide catalyst present in an amount of at least 0.5 mole percent based on the reacting monomers plus an aldehyde having the formula wherein R is selected from the group consisting of hydrogen, hydrocarbon radicals, and aldehyde-substituted hydrocarbon radicals, present in an amount of at least 3 mole percent based on the reacting monomers, continuing said polymerization conditions until essentially all the '14 polymerization islefiected mm presence ofan aromatic hydrocarbon diluent.

12. A process according to claim 11 wherein said diluentis benzene. I V p 13. A process according toclaim 8 whereinsaidcopolymerization is effected in the presence of a halogenated aliphatic hydrocarbon diluent, 1

14. A process for'the production oil low molecular weightethylene/maleic anhydride copolymer in .,the j form of non-agglomerated particles and'having a specific viscosity as determined in 1 weight percent solution in dimethylformamide of about 0.1, which comprises subjecting maleic anhydride, ethylene, and a peroxide catalyst, dissolved in a liquid composed of a liquid chlorinated aliphatic hydrocarbon solvent and a liquid alkanal having at least one hydrogen atom on the a-carbon atom, to polymerization reaction at a temperature within the range of 60 to C. while maintained at an ethylene pressure of from to 200 pounds per square inch, said catalyst being present in an amount of at least 0.5 mole percent based on the reacting monomers and said alkanal being present in an amount of at least 6 mole percent based on the reacting monomers, separating resultant polymer particles from the liquid reaction medium, and returning thus-separated liquid to the polymerization where said aldehyde, unused catalyst, and any unreacted maleic anhydride take part in the polymerization reaction to produce more of said low molecular weight copolymer.

15. A process according to claim 14 in which chlorinated aliphatic hydrocarbon solvent is ethylene dichloride and said alkanal is a butyraldehyde.

16. A process which comprises subjecting maleic anhydride and isobutylene to copolymerization at a temperature within the range of 40 to 80 C. with the aid of a peroxide catalyst and in the presence of an aldehyde having the formula wherein R is selected from the group consisting of hydrogen, hydrocarbon radicals, and aldehyde-substituted hydrocarbon radicals, present in an amount of at least 5 mole percent based on the reacting monomers, continuing said polymerization conditions until essentially all the monomer present in the lesser molar amount has been copolymerized, and recovering as a product of the process an isobutylene/maleic anhydride copolymer in essentially theoretical yield and having a specific viscosity as determined in 1 weight percent solution in dimethylformamide at 25 C. of not in excess of about 1.

17. A process which comprises subjecting maleic anhydride maintained under a propylene pressure of at least about 40 pounds per square inch and at a temperature within the range of 60 to 80 C. to polymerization with the aid of a peroxide catalyst present in an amount of at least 0.2 mole percent based on the reacting monomers plus an aldehyde having the formula wherein R is selected from the group consisting of hydrogen, hydrocarbon radicals, and aldehyde-substituted hy' drocarbon radicals, present in an amount of at least 5 'mole percent based on the reacting monomers, continuing said polymerization conditions until essentially all the maleic anhydride has been copolymerized with propylene,

and recovering as a product of the process a propylene/ maleic anhydride copolymer in essentially theoretical yield and having a specific viscosity as determined in 1 weight percent solution in dimethylformamide at 25 C. of not in excess of about 0.4.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Hanford Apr. 10, 1945 Hanford June 19, 1949 Tawney Nov. 27, 1951 McQueen June 3, 1952 Danzig et a1. Nov. 4, 1952 Barrett Apr. 13, 1954 Popkin ct a1. Oct. 25, 1955 OTHER REFERENCES 

1. IN THE COPOLYMERIZATION OF MALEIC ANHYDRIDE WITH AN OLEFIN HAVING FROM 2 TO 4 CARBON ATOMS WITH THE AID OF A FREE-RADICAL PROMOTING CATALYST TO FORM AN OLEFIN/ MALEIC ANHYDRIDE COPOLYMER, THE IMPROVEMENT WHICH COMPRISES EFFECTING SAID COPOLYMERIZATION AT A TEMPERATURE WITHIN THE RANGE OF 40 TO 80*C. AND IN THE PRESENCE OF AN ALDEHYDE HAVING THE FORMULA 